View field offset camera system

Abstract

The utility model discloses a camera system with a field of view offset. The camera system at least comprises an image acquisition unit and an imaging lens which are arranged front and back, the position relation between the image acquisition unit and the imaging lens is set, so that the center of the imaging lens has deviation in the vertical direction relative to the center of the image acquisition unit; the plane where the imaging lens or / and the image acquisition unit are located is inclined in the pitching direction, so that an included angle is formed between the plane where the imaging lens is located and the plane where the image acquisition unit is located, and the included angle extends and intersects at an intersection line which is close to one side of a target view area. According to the camera system with the field-of-view offset, the field-of-view adjustment can be realized without inclining the main body of the camera system, and the problems of perspective deformation, magnification imbalance and the like caused by the fact that the camera has to be rotated due to the field-of-view requirement on the inclined lower part or the side part of the camera can be solved.

Description

Technical Field

[0001] The utility model relates to the field of vehicle-mounted photography, in particular to a photography system with a field of view offset. Background Art

[0002] When shooting, a camera system typically faces the subject directly, with the object plane parallel to the image plane. This shooting method is called "normal shooting." However, in some specific application scenarios, this "normal shooting" approach may not deliver optimal results. For example, if the object is fixed, the camera must tilt and yaw to capture it. This can cause perspective distortion in the image, affecting parameters such as aspect ratio and magnification.

[0003] For example, with the advancement of electronic camera technology, more and more vehicles are adding auxiliary cameras. To capture objects below, closer to the vehicle, or to capture a view farther away from the vehicle, the camera must be installed in a non-perpendicular orientation, tilted toward the ground or outward from the vehicle. This installation method causes the camera's focal plane to be off-center from the subject. When the camera's focal plane is not parallel to the subject's plane, the camera must tilt and yaw to capture the subject. This distorts the subject's perspective in the image, severely affecting image parameters such as aspect ratio, magnification, and MTF.

[0004] Take the grid test board as an example; when shooting the vertical grid test board at an angle, the center of the lens optical axis and the center of the grid test board are displaced, and the grid test board appears in the image with perspective distortion (called vertical convergence distortion and horizontal convergence distortion in the photography world) with the top larger and the bottom smaller, and the left smaller and the right larger. This causes an imbalance in the aspect ratio and magnification.

[0005] If the camera is mounted at an angle, the magnification and aspect ratio of the captured object will be unbalanced, requiring software correction. Writing software code is labor-intensive and requires significant computing power to run. High-computing chips reduce the number of models available and increase purchase costs. Furthermore, high computing power increases power consumption, making thermal management a major pain point in electronic system design. Furthermore, running large amounts of graphics code increases the likelihood of product bugs. Utility Model Content

[0006] To address the aforementioned issues, the present invention aims to provide a camera system that can adjust the field of view without tilting the camera body. This system can address issues such as perspective distortion and magnification imbalance caused by tilting the camera body downward and / or tilting the camera sideways to meet the required field of view. The present camera system can conserve image acquisition unit resources and reduce the workload of writing and developing image correction software.

[0007] Principle Description

[0008] During the research and development process, the inventors noticed that in a rearview camera device, the demand for the field of view below, to the outside, and to the rear of the vehicle is greater than the demand for the field of view above and to the inside of the vehicle.

[0009] In order to obtain a view further below the vehicle, the rearview camera often needs to be tilted downward, which in turn causes perspective distortion. In order to reduce the perspective distortion problem and increase the field of view below the camera device, the inventors proposed a forward shooting method.

[0010] That is, first, an imaging lens with a large clear imaging circle area is selected, so that the diameter of the clear imaging circle of the imaging lens is greater than k times the diagonal length of the image acquisition unit (k is a proportional coefficient, a constant greater than 1, preferably set to 1.2-2.5, and more preferably 1.3). This allows the image acquisition unit to perform a certain translation operation on the rear focal plane of the imaging lens, so that the image acquired at the outermost position of the image acquisition unit after the image is offset within the clear imaging circle still meets the image quality requirements in terms of distortion, MTF value and other parameters.

[0011] Then, the positional relationship between the imaging lens and the image acquisition unit is adjusted so that the image acquisition unit has a vertical offset relative to the imaging lens. Specifically, under normal circumstances, the imaging lens and the image acquisition unit are coaxial, and the projection of the optical axis of the imaging lens on the image acquisition unit is located at the center of the image acquisition unit. However, in this patent, the image acquisition unit is moved upward relative to the imaging lens so that the center of the imaging lens is located vertically below the center of the image acquisition unit. This relative offset can also be achieved by moving the imaging lens downward relative to the image acquisition unit.

[0012] Finally, in order to obtain a larger depth of field within the target field of view, that is, to image a wider range of scenes more clearly within the required field of view, a slight pitch setting is made in the imaging lens and the image acquisition unit, that is, the imaging lens is slightly tilted in the pitch direction relative to the image acquisition unit, or the image acquisition unit is slightly tilted in the pitch direction relative to the imaging lens, so that the planes where the two are located are not completely parallel, but there is a small angle between them, and the intersection line of the two planes is located on the upper and lower sides of the two, preferably below, so that the object focal plane of the camera system (that is, the plane of the subject), the plane where the imaging lens is located, and the plane where the image acquisition unit is located intersect in a straight line, and thus the arrangement of the image acquisition unit and the imaging lens satisfies Scham's law.

[0013] With this arrangement, the object-side focal plane of the camera system will be a substantially horizontally extending plane extending from the intersection line below the camera system to the front of the camera system, thereby obtaining a larger effective and clear camera range.

[0014] Based on the above principles, this patent provides a camera system with a field of view offset, which includes at least an image acquisition unit and an imaging lens arranged in front and back;

[0015] Setting a positional relationship between the image acquisition unit and the imaging lens so that the center of the imaging lens is offset in a vertical direction relative to the center of the image acquisition unit;

[0016] The plane where the imaging lens and / or the image acquisition unit are located is tilted in the pitch direction, so that there is an angle between the plane where the imaging lens and the plane where the image acquisition unit are located, and they intersect at an intersection line, which is close to one side of the target field of view area.

[0017] In a preferred implementation, the object-side focal plane of the camera system intersects the plane where the imaging lens is located and the plane where the image acquisition unit is located at the intersection line.

[0018] In another preferred implementation, the center of the imaging lens is offset downward relative to the center of the image acquisition unit, and the intersection of the object focal plane of the camera system, the plane where the imaging lens is located, and the plane where the image acquisition unit is located is located below or diagonally below the camera system.

[0019] In another preferred implementation, the diameter of the clear imaging circle of the imaging lens is greater than or equal to a predetermined multiple of the diagonal length of the image acquisition unit, so that the image acquisition unit can still obtain image quality that meets regulatory standards after being offset within the clear imaging circle.

[0020] In another preferred implementation, the center of the imaging lens is offset in a horizontal direction relative to the center of the image acquisition unit.

[0021] In another preferred implementation, at least one of the imaging lens and the image acquisition unit has a horizontal deflection angle, so that there is a horizontal angle between the two.

[0022] In another preferred implementation, the included angle in the pitch direction caused by the tilt between the imaging lens and / or the image acquisition unit is 0.1-5 degrees, and the vertical position offset distance Y0 is 0.1-5 mm.

[0023] In another preferred implementation, the vertical position offset distance Y0 ≥ f1(β+α), where f1 is a function of the relationship between the image height of the imaging lens at the current image acquisition unit position and the longitudinal field of view angle, β is the angle between the optical axis of the imaging lens and the lower edge of the field of view in the vertical plane, and α is the angle between the plane where the imaging lens is located and the plane where the image acquisition unit is located.

[0024] In another preferred implementation, the predetermined multiple is 1.2-2.5 times.

[0025] In another preferred implementation, the predetermined multiple is 1.3-2 times.

[0026] In another preferred implementation, the camera system is set forward for shooting.

[0027] The forward direction here refers to the direction relative to the primary shooting area. For example, in a rearview mirror, the primary shooting area is directly behind the camera, so the direction directly behind the camera is defined as the forward direction. In other application scenarios, the primary shooting direction can be defined as the forward direction.

[0028] It should be noted that the "intersection line" of the object focal plane of the camera system, the plane where the imaging lens is located, and the plane where the image acquisition unit is located mentioned in the present invention is not an idealized intersection line, and a certain error is allowed to exist. It means that the planes where the three are located roughly intersect in a straight line, and the intersection line can have a certain range interval.

[0029] In this application, "the intersection line is close to the side of the target field of view area" means that the intersection line of the plane where the image acquisition unit and the imaging lens are located is located on the side where the user wants to capture more scenery. For example, if the user wants to capture more scenery below the imaging system, the intersection line is located below the imaging system, and so on.

[0030] The “plane where the imaging lens is located” refers to the plane passing through the center of the imaging lens and perpendicular to the optical axis of the imaging lens.

[0031] It should be noted that the “deflection” mentioned in this application refers to the rotation around a vertical axis.

[0032] The “offset” mentioned in this application refers to the relative translation of the image acquisition unit and the imaging lens within the mounting plane, with the translation direction being perpendicular to the main axis of one of them, which can be adjusted according to the specific mounting method of the camera.

[0033] Of course, those skilled in the art should understand that in the embodiment of the present application, the center of the image acquisition unit of the camera system is offset upward relative to the intersection of the optical axis of the imaging lens and the plane where the image acquisition unit is located. This is to provide a field of view below the vehicle. However, those skilled in the art can adjust the direction and angle of the vertical offset according to the specific application scenario when applying it to other scenarios.

[0034] Those skilled in the art should understand that since offset is a relative concept, the offset of the image acquisition device relative to the main axis of the imaging lens can be achieved by moving the image acquisition unit or by moving the imaging lens in the opposite direction.

[0035] Beneficial effects

[0036] The camera device with the field of view offset setting of the present invention can achieve field of view adjustment without tilting the main body of the camera system. It can solve the problems of perspective distortion and magnification imbalance caused by having to tilt the camera due to the need for a field of view diagonally below or to the side of the camera.

[0037] This patent uses vertical translation to replace the current tilt-down operation of existing cameras, avoiding the perspective distortion caused by the overall tilt operation and achieving the downward shift of the target field of view. The camera device using the field of view offset setting of the utility model can maximize the effective area of ​​the image acquisition unit.

[0038] In addition, for application scenarios that require more side shots, the imaging lens and / or image acquisition unit may be appropriately deflected (instead of deflecting the entire camera mechanism) to better shoot the side shots. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the positional relationship between the lens and the image acquisition unit in an existing ordinary camera. Figure 1 The upper middle portion is a schematic view (or main view) from the image acquisition unit toward the lens; the lower portion is a top view cross-sectional view;

[0040] Figure 2 Schematic diagram of the positional relationship between the lens and the image acquisition unit in the vehicle-mounted camera device in Example 1 of the present application. Figure 2 The upper left center diagram is a schematic diagram of the positional relationship between the image acquisition unit and the lens (or a main view) viewed from the image acquisition unit toward the lens; the lower center diagram is a top view, and the upper right diagram is a left view (the same below);

[0041] Figure 3 Schematic diagram of the positional relationship between the image acquisition unit and the clear imaging circle of the imaging lens.

[0042] Figure 4 Schematic diagram of the arrangement of the imaging lens relative to the image acquisition unit in Example 2 of the present utility model;

[0043] Figure 5 Schematic diagram of the arrangement of the imaging lens relative to the image acquisition unit in Example 3 of the present utility model;

[0044] Figure 6 Schematic diagram of the positional relationship between the imaging lens and the image acquisition unit in Example 4 of the present application.

[0045] Figure 7This is a view of the angle and position relationship when the camera system is installed on the vehicle. DETAILED DESCRIPTION

[0046] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0047] Figure 1 The figure shows the positional relationship between the lens and the image acquisition unit in the conventional camera device. As can be seen from the figure, the center of the lens 30 in the conventional camera device is horizontally aligned with the center of the image acquisition unit, and the lens 30 has no vertical offset relative to the center of the image acquisition unit 20.

[0048] Example 1

[0049] Figure 2 This is a schematic diagram showing the positional relationship between the lens and the image acquisition unit in the offset-arranged vehicle-mounted camera device in Example 1 of the present utility model, wherein the image acquisition unit is offset upward.

[0050] The vehicle-mounted camera device with field of view offset in this embodiment includes an image acquisition unit 20 ( Figure 2 In section A of the camera, the image acquisition unit 20 is represented by a wireframe and the imaging lens 30 is mounted sequentially within the camera housing. A mounting base is provided in the middle or rear portion of the camera housing, and a mounting position for the image acquisition unit is provided on the camera mainboard. The image acquisition unit 20 is mounted within this mounting position.

[0051] like Figure 3 The figure shows a schematic diagram of the relationship between the clear imaging circle and the image acquisition unit. Compared with the existing camera device, in this embodiment, the clear imaging circle size (diameter) of the lens 30 in the camera system is larger than the diagonal length of the image acquisition unit. Preferably, the diameter of the clear imaging circle of the lens is larger than 1.3 times the diagonal length of the image acquisition unit. The description here is based on a circular lens and a rectangular image acquisition unit as an example. If lenses and image acquisition units of other shapes are used, it is necessary to ensure that the maximum diagonal length of the imaging area is larger than a predetermined multiple of the maximum diagonal length of the image acquisition unit to ensure that the image acquisition unit can be translated within the imaging area. And the parameters such as distortion and MTF value of the image captured at the outermost position of the image acquisition unit after the offset within the clear imaging circle still meet the image quality requirements.

[0052] The horizontal projection position O' of the center of the lens 30 on the image acquisition unit 20 does not coincide with the center O of the image acquisition unit. The center of the image acquisition unit is offset upward relative to the horizontal projection position of the center of the lens 30 on the image acquisition unit 20. The line connecting O' is the offset of the image acquisition unit 20. Alternatively, O' may represent the intersection of the optical axis of the lens 30 on the image acquisition unit 20.

[0053] The vertical offset distance OO' is ≥ f1(β+α), where f1 is the relationship between the image height of the imaging lens at the current image acquisition unit position and the longitudinal field of view angle. β is the angle in the vertical plane between the optical axis of the imaging lens and the lower edge of the field of view. α is the angle between the plane of the imaging lens and the plane of the image acquisition unit. Typically, the vertical offset distance OO' is 0.1-5 mm.

[0054] In fact, β+α is the angle between the horizontal line and the edge of the field of view below in the vertical plane.

[0055] Figure 3 In the figure, X and Y are the horizontal and vertical lengths of the image acquisition unit, respectively. Y0 is the ordinate of the edge position in the offset direction of the image acquisition unit or the longitudinal distance between the edge position in the offset direction of the image acquisition unit and the projection point of the imaging lens center on the image acquisition unit.

[0056] This offset is predetermined during camera design and implemented during installation of the imaging lens and image acquisition unit. This offset is achieved by translating the imaging lens or image acquisition unit. While this embodiment describes the translation of the image acquisition unit as an example, those skilled in the art will appreciate that this translation can also be achieved by translating the imaging lens.

[0057] Specifically, during design, the center of the image acquisition unit is offset in the vertical direction relative to the center of the imaging lens, and the offset direction is generally perpendicular to the optical axis of the imaging lens.

[0058] The verification of each actual effect in this application was shot under the same real-scene layout conditions. The target area was set with two letter identification blocks (front and back), four cone barrels (two at far and two at near, located on the left and right sides of the front respectively) and a checkered plate (located directly in front).

[0059] Experiments have confirmed that when shooting from the front, the two cone barrels closest to the camera system cannot be captured at all, and the first letter logo closest to it cannot be captured either.

[0060] In contrast, after the image acquisition unit is vertically offset upward, it can capture the two cone barrels closest to the camera system and the first letter logo at the front. However, the clarity of the first letter logo at the front is slightly lower.

[0061] Example 2

[0062] like Figure 4 The figure shows the positional relationship between the imaging lens and the image acquisition unit in Example 2 of the present application. In this embodiment, the image acquisition unit is not only offset upward, but also tilted downward, meaning that one of the two undergoes a pitch change. In this embodiment, when the pitch angle is adjusted, the plane of the imaging lens, the plane of the image acquisition unit, and the object focal plane of the camera system intersect on a single intersection line. This satisfies Schaum's law and achieves the largest clear imaging area.

[0063] This can be verified from the actual shooting effect after the image acquisition unit is vertically offset upward and the imaging lens has a downward angle. It can not only capture the two cones closest to the camera system, but also the first letter logo at the front, and the clarity of the first letter logo at the front is significantly improved.

[0064] Judging from the actual shooting results, the perspective distortion is smaller than when the camera system is shooting from above.

[0065] Example 3

[0066] like Figure 5 The figure shows the positional relationship between the imaging lens and the image acquisition unit in Example 3 of the present application. In this embodiment, the image acquisition unit is not only offset upward, but the imaging lens has a downward tilt angle, that is, one of the two undergoes a pitch change, and the image acquisition unit is offset to one side.

[0067] Actual shooting results with the image acquisition unit offset vertically upward and to the left, and the imaging lens positioned at a top-down angle, confirm that shifting the shooting position to the left is suitable for side-on shooting. This not only captures the two cones closest to the camera system and the first letter of the logo in the foreground, but also allows installation on the side of an object, such as a car body, to capture the scenery on the other side with a wider field of view.

[0068] Example 4

[0069] like Figure 6Figure 4 shows the positional relationship between the imaging lens and the image acquisition unit in Example 4 of the present application. In this embodiment, the image acquisition unit is not only offset upward, but the imaging lens is also tilted downward and to the right. That is, one of the two lenses undergoes pitch and yaw changes, and the image acquisition unit is offset to one side.

[0070] In this case, in order to satisfy Schaam's law, the plane where the imaging lens is located, the plane where the image acquisition unit is located, and the object focal plane of the camera system still intersect at an intersection line, which is located diagonally below the right side of the camera system.

[0071] This is demonstrated by the actual shooting results of this embodiment, where the image acquisition unit is offset vertically upward and horizontally to the left, and the imaging lens has both a top-down and a yaw angle. When the camera system is positioned to the left of the target scene, it can capture not only the two cones closest to the camera system, but also the first letter logo at the front. This makes it more convenient to install it on the side of an object, such as the side of a car body, allowing it to capture scenes on the other side (the outside of the car body) with a wider field of view.

[0072] Figure 7 These are the angular relationships in the vertical plane when the camera system is applied to a vehicle. A represents the center of the lens, B represents the projection of the lens center on the ground, C represents the desired edge of the field of view below, β is the angle between the lens optical axis and the edge of the field of view, and α is the angle between the lens optical axis and the horizontal direction.

[0073] In summary, it can be seen that the use of the translation and pitch vehicle-mounted camera system of this application can reduce perspective distortion, obtain high-definition images, expand the effective field of view area, save image acquisition unit resources, reduce the amount of image correction software code writing, and reduce the delay caused by video processing.

[0074] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative of the implementation of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solutions of the present invention fall within the scope of protection of the present invention.

Claims

1. A camera system with a field of view shift, comprising at least an image acquisition unit and an imaging lens disposed front and rear; characterized in that: Setting a positional relationship between the image acquisition unit and the imaging lens so that the center of the imaging lens is offset in a vertical direction relative to the center of the image acquisition unit; The plane where the imaging lens and / or the image acquisition unit are located is tilted in the pitch direction, so that there is an angle between the plane where the imaging lens is located and the plane where the image acquisition unit is located, and then they extend and intersect at an intersection line, which is close to one side of the target field of view area.

2. The camera system with field of view shift according to claim 1, characterized in that: The object focal plane of the camera system intersects with the plane where the imaging lens is located and the plane where the image acquisition unit is located at the intersection line.

3. The camera system with field of view shift according to claim 2, characterized in that: The center of the imaging lens is offset downward relative to the center of the image acquisition unit, and the intersection of the object focal plane of the camera system, the plane where the imaging lens is located, and the plane where the image acquisition unit is located is located below or obliquely below the camera system.

4. The camera system with field of view shift according to claim 1, wherein: The diameter of the clear imaging circle of the imaging lens is greater than or equal to a predetermined multiple of the diagonal length of the image acquisition unit, so that the image acquisition unit after displacement can still fall within the clear imaging circle of the imaging lens.

5. The camera system with field of view shift according to claim 1, wherein: The center of the imaging lens is offset in a horizontal direction relative to the center of the image acquisition unit.

6. The camera system with field of view shift according to any one of claims 1 to 5, characterized in that: At least one of the imaging lens and the image acquisition unit has a horizontal deflection angle, so that there is a horizontal angle between the two.

7. The camera system with field of view shift according to claim 1, wherein: The included angle in the pitch direction caused by the tilt between the imaging lens and / or the image acquisition unit is 0.1-5 degrees, and the vertical offset distance Y0 is 0.1-5 mm.

8. The camera system with field of view shift according to claim 1, wherein: The vertical position offset distance Y0≥f1(β+α), where f1 is the relationship function between the image height of the imaging lens at the current image acquisition unit position and the longitudinal field of view angle, β is the angle between the optical axis of the imaging lens and the lower edge of the field of view in the vertical plane, and α is the angle between the plane where the imaging lens is located and the plane where the image acquisition unit is located.

9. The camera system with field of view shift according to claim 4, characterized in that: The predetermined multiple is 1.2-2.5 times.

10. The camera system with field of view shift according to claim 9, characterized in that: The predetermined multiple is 1.3-2 times.

11. The camera system with field of view shift according to claim 1, characterized in that: The camera system is set forward to shoot.

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